A chiral gold nanocluster Au20 protected by tetradentate phosphine ligands

Alkynyl-protected silver nanoclusters featuring an anticuboctahedral kernel

Two unique silver nanoclusters protected by alkynyl and diphosphine ligands have been synthesized. Single crystal structural determination reveals that they have a centered anticuboctahedral Ag₁₃ kernel. Such a kernel is observed for the first time in a coinage metal nanocluster. This work offers new insights into the fact that the PhC[triple bond, length as m-dash]C ligand represents a new direction in synthesizing novel metal nanoclusters.

A novel double-helical-kernel evolution pattern of gold nanoclusters: alternate single-stranded growth at both ends

Studying the kernel evolution pattern of gold nanoclusters is intriguing but challenging due to the difficulty of precise size control and structure resolution. Herein, we successfully synthesized two novel gold nanoclusters, Au₃₄(S-c-C₆H₁₁)₂₂ and Au₄₂(S-c-C₆H₁₁)₂₆ (S-c-C₆H₁₁: cyclohexanethiolate), and resolved their structures. Interestingly, it was found that the kernel evolves from Au₂₈(S-c-C₆H₁₁)₂₀ to Au₃₄(S-c-C₆H₁₁)₂₂ and Au₄₂(S-c-C₆H₁₁)₂₆ in a novel fashion: alternate single-stranded evolution at both ends, which is remarkably different from the reported double-stranded growth at the bottom for the 4-tert-butylbenzenethiolate (TBBT)-protected nanocluster series. This work illustrates the variety of kernel evolution patterns and the directionality of the ligands with respect to the evolution of the kernel. In addition, differential pulse voltammetry (DPV) revealed that the electrochemical gap between the first oxidation and the first reduction potential decreases as the size increases from Au₂₈(S-c-C₆H₁₁)₂₀ to Au₃₄(S-c-C₆H₁₁)₂₂ and Au₄₂(S-c-C₆H₁₁)₂₆.

Theoretical investigations on the structure–property relationships of Au13and AuxM13−xnanoclusters

The effect of ligands and dopants on Au_xM_13−xNCs was studied by DFT and TD-DFT calculations.

Peculiar holes on checkerboard facets of a trigonal prismatic Au9Ag36(SPhCl2)27(PPh3)6cluster caused by steric hindrance and magic electron count

A trigonal-prismatic Au–Ag bimetallic nanocluster, Au₉Ag₃₆(SPhCl₂)₂₇(PPh₃)₆, having “holes” on the ligand shell was prepared and crystallographically characterized.

Gold-doped silver nanocluster [Au3Ag38(SCH2Ph)24X5]2- (X = Cl or Br)

Here we report the single-crystal structure, experimental and theoretical characterization of a 41-metal atom Au-Ag alloy nanocluster [Au₃Ag₃₈(SCH₂Ph)₂₄X₅]^2- (1, X = Cl or Br). The nanocluster 1 is co-protected by thiolate and halogen atoms and features an all-metallic face-fused biicosahedral Au₂@AuAg₂₀ rod-like kernel enwrapped by the outermost Ag₁₈(SCH₂Ph)₂₄X₃ shell. Two sites on the surface of the biicosahedral kernel are partially occupied by Au and Ag atoms. The outer Ag₁₈(SCH₂Ph)₂₄X₃ shell is composed of two Ag₆S₆ cycles at the two poles and one Ag₆S₂X₃ arc at the equator with both 2- and 3-coordinated Ag atoms, which has not been observed in gold or silver nanoclusters ever before. Theoretical calculations elucidate its electronic structure as well as optical properties, thus producing informative correlations between its structure and properties. This nanocluster exhibits near-infrared (NIR) emission around 825 nm. This work (i) snapshots a rare crystal structure of an Au-doped silver alloyed nanocluster; (ii) gives a deep insight to understand how the capping ligand or anions affect the structure of the alloy nanocluster; and (iii) provides precise information about gold atom doping site that is very significant in the recognition of potential active catalytic sites of the alloy nanoparticles.

A grand unified model for liganded gold clusters

A grand unified model (GUM) is developed to achieve fundamental understanding of rich structures of all 71 liganded gold clusters reported to date. Inspired by the quark model by which composite particles (for example, protons and neutrons) are formed by combining three quarks (or flavours), here gold atoms are assigned three 'flavours' (namely, bottom, middle and top) to represent three possible valence states. The 'composite particles' in GUM are categorized into two groups: variants of triangular elementary block Au₃(2e) and tetrahedral elementary block Au₄(2e), all satisfying the duet rule (2e) of the valence shell, akin to the octet rule in general chemistry. The elementary blocks, when packed together, form the cores of liganded gold clusters. With the GUM, structures of 71 liganded gold clusters and their growth mechanism can be deciphered altogether. Although GUM is a predictive heuristic and may not be necessarily reflective of the actual electronic structure, several highly stable liganded gold clusters are predicted, thereby offering GUM-guided synthesis of liganded gold clusters by design.

Amplification of the Optical Activity of Gold Clusters by the Proximity of BINAP

Despite recent progress in the synthesis and characterization of optically active gold clusters, the factor determining optical rotatory strength has not been clarified due to the lack of structurally resolved, enantiomerically pure Au clusters. We addressed this issue by studying the correlation between the optical activity and geometrical structures of two types of Au clusters that were protected by chiral diphosphines: [Au₁₁(R/S-DIOP)₄Cl₂]⁺ (DIOP = 1,4-bis(diphenylphosphino)-2,3-o-isopropylidene-2,3-butanediol) and [Au₈(R/S-BINAP)₃(PPh₃)₂]²⁺ (BINAP = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl). [Au₈(BINAP)₃(PPh₃)₂]²⁺ showed stronger rotatory strengths than [Au₁₁(DIOP)₄Cl₂]⁺ in the visible region, while the Hausdorff chirality measure calculated from the crystal data indicated that the Au core of the former is less chiral than that of the latter. We propose that the optical activity in the Au core-based transition due to the deformed core is further amplified by chiral arrangement of the binaphthyl moiety near the Au core.

Nanoscale chirality in metal and semiconductor nanoparticles

The field of chirality has recently seen a rejuvenation due to the observation of chirality in inorganic nanomaterials. The advancements in understanding the origin of nanoscale chirality and the potential applications of chiroptical nanomaterials in the areas of optics, catalysis and biosensing, among others, have opened up new avenues toward new concepts and design of novel materials. In this article, we review the concept of nanoscale chirality in metal nanoclusters and semiconductor quantum dots, then focus on recent experimental and theoretical advances in chiral metal nanoparticles and plasmonic chirality. Selected examples of potential applications and an outlook on the research on chiral nanomaterials are additionally provided.

Polynuclear Gold [Au(I) ]4 , [Au(I) ]8 , and Bimetallic [Au(I) 4 Ag(I) ] Complexes: C-H Functionalization of Carbonyl Compounds and Homogeneous Carbonylation of Amines

The synthesis of tetranuclear gold complexes, a structurally unprecedented octanuclear complex with a planar [Au(I) 8 ] core, and pentanuclear [Au(I) 4 M(I) ] (M=Cu, Ag) complexes is presented. The linear [Au(I) 4 ] complex undergoes C-H functionalization of carbonyl compounds under mild reaction conditions. In addition, [Au(I) 4 Ag(I) ] catalyzes the carbonylation of primary amines to form ureas under homogeneous conditions with efficiencies higher than those achieved by gold nanoparticles.

Polymorphism of Phosphine-Protected Gold Nanoclusters: Synthesis and Characterization of a New 22-Gold-Atom Cluster

A new Au22 nanocluster, protected by bis(2-diphenyl-phosphino)ethyl ether (dppee or C28 H28 OP2 ) ligand, has been synthsized and purified with high yield. Electrospray mass spectrometry shows that the new cluster has a formula of Au22 (dppee)7 , containing 22 gold atoms and seven dppee ligands. The cluster is found to be stable as a solid, but metastable in solution. The new cluster has been characterized by UV-Vis-NIR absorption spectroscopy, collision-induced dissociation, and (31) P-NMR. The properties of the new cluster have been compared with the previous Au22 (dppo)6 nanocluster (dppo = 1,8-bis(diphenyl-phosphino)octane or C32 H36 P2 ), which contains two fused Au11 units. All the experimental data indicate that the new Au22 (dppee)7 cluster is different from the previously known Au22 (dppo)6 cluster and represents a new Au22 core, which contains most likely one Au11 motif with several Au2 (dppee) or Au(dppee) units. The Au22 (dppee)7 cluster provides a new example of the ligand effects on the nuclearity and structural polymorphism of phosphine-protected atom-precise gold nanoclusters.

Chiral chemistry of metal-camphorate frameworks

This critical review presents the various synthetic approaches and chiral chemistry of metal-camphorate frameworks (MCamFs), which are homochiral metal-organic frameworks (MOFs) constructed from a camphorate ligand. The interest in this unique subset of homochiral MOFs is derived from the many interesting chiral features for both materials and life sciences, such as asymmetrical synthesis or crystallization, homochiral structural design, chiral induction, absolute helical control and ligand handedness. Additionally, we discuss the potential applications of homochiral MCamFs. This review will be of interest to researchers attempting to design other homochiral MOFs and those engaged in the extension of MOFs for applications such as chiral recognition, enantiomer separation, asymmetric catalysis, nonlinear sensors and devices.

Syntheses, structures, luminescence and magnetic properties of three high-nuclearity neodymium compounds based on mixed sulfonylcalix[4]arene-phosphonate ligands

The solvothermal reactions of p-tert-butylsulfonylcalix[4]arene (H₄BSC4A), phosphonic acid and neodymium chloride have resulted in three novel high-nuclearity neodymium coordination compounds.

Tri-icosahedral Gold Nanocluster [Au37(PPh3)10(SC2H4Ph)10X2](+): Linear Assembly of Icosahedral Building Blocks

The [Au37(PPh3)10(SR)10X2](+) nanocluster (where SR = thiolate and X = Cl/Br) was theoretically predicted in 2007, but since then, there has been no experimental success in the synthesis and structure determination. Herein, we report a kinetically controlled, selective synthesis of [Au37(PPh3)10(SC2H4Ph)10X2](+) (counterion: Cl(-) or Br(-)) with its crystal structure characterized by X-ray crystallography. This nanocluster shows a rod-like structure assembled from three icosahedral Au13 units in a linear fashion, consistent with the earlier prediction. The optical absorption and the electrochemical and catalytic properties are investigated. The successful synthesis of this new nanocluster allows us to gain insight into the size, structure, and property evolution of gold nanoclusters that are based upon the assembly of icosahedral units (i.e., cluster of clusters). Some interesting trends are identified in the evolution from the monoicosahedral [Au13(PPh3)10X2](3+) to the bi-icosahedral [Au25(PPh3)10(SC2H4Ph)5X2](2+) and to the tri-icosahedral [Au37(PPh3)10(SC2H4Ph)10X2](+) nanocluster, which also points to the possibility of achieving even longer rod nanoclusters based upon assembly of icosahedral building blocks.